1. Technical Field of the Invention
The present invention relates to a technology for allowing an image processor provided in an amusement apparatus to display images on a display device, and more particularly to a control method, apparatus and program allowing an image processor to display images on two display devices employing different frame rates.
2. Description of the Related Art
Some personal computers or the like have a dual screen function to allow images to be displayed on two display devices. An amusement apparatus such as a game console having such a dual screen function has been proposed recently.
However, in some cases, an electronic apparatus such as an amusement apparatus requires a function to display moving images on two display devices having different time frame lengths (vertical scanning periods). To meet this requirement, the apparatus may include two image processors that generate image data to be displayed on two display devices and may be constructed to allow the two image processors to operate in parallel. However, such an apparatus including two image processors is expensive. Therefore, for example, an apparatus may be constructed so as to allow one image processor to perform two types of drawing (or rendering) processes for generating image data to be displayed on two display devices using, as a trigger, switching of shorter frames among different-length frames of the two display devices. However, when the frame lengths of the two display devices are different, the phase relationship between frames of the displays changes from moment to moment. Therefore, image data of a screen to be displayed on a display device which operates with long frames may not be generated in time for the start of a frame for displaying the image data of the screen, failing to display the screen and thus causing frame (or screen) dropping or skipping.